New genus and species of theropod dinosaur named Antebi Sukuri Longs has been reported by a team of researchers from the National University of San Juan, the Bernardino Rivadavia Museum of Natural Sciences, the University of Birmingham, CONICET, and CIGEOBIO.
Antebi Sukuri Longs inhabited the Earth during the Carnian period of the late Triassic, approximately 231 to 226 million years ago.
This dinosaur measured about 1.2 meters (4 feet) in length and weighed around 8 to 9 kilograms.
The species represents an early-diverging theropod outside the Neoheteropod group, with functional traits previously believed to be exclusive to that classification surprisingly derived.
“This is among the oldest and most primitive dinosaurs yet discovered,” stated Dr. Ricardo Martinez from San Juan National University and his team.
“The early diversification of dinosaurs triggered significant ecological transformations in terrestrial ecosystems, culminating in the dominance of dinosaurs in tetrapod populations by the Triassic-Jurassic boundary 201 million years ago.”
“Therefore, investigating the early diversification of dinosaurs is crucial for understanding the formation of Mesozoic populations.”
“Nonetheless, the absence of stratigraphically continuous fossil data in different geological formations, where the oldest known dinosaurs (dating from 233 to 227 million years ago) are found, has hindered our comprehension of this early diversification.”
Paleontologists uncovered fossilized remains of Antebi Sukuri Longs—including a partial skeleton and skull—discovered in 2014 within the Izquiguarasto formation in northwestern Argentina.
“Few locations in the world offer such ancient and well-preserved fossils,” Martinez remarked.
“One notable site is the Santa María Formation in Rio Grande do Sul, Brazil, and the other is the Izquiguarasto Formation.”
Antebi Sukuri Longs thrived around 2 million years after Earth’s formation in a warm, arid savannah, experiencing episodes from the Carnian rainy season.
“We demonstrate that dinosaur diversity and abundance in the Iskigualast Formation were greater than previously acknowledged, particularly among smaller herbivores (under 30 kg) and medium-sized predators (30 kg to 200 kg),” the researchers stated.
“This diversification took place in Iskigualast during a transition to semi-arid conditions, but a return to wetter conditions created a gap in the dinosaur record beginning around 229 million years ago.”
“Only 15 million years later, during the mid-Norian period, the abundance and diversity of dinosaurs in the basin rebounded, this time characterized by larger-bodied species.”
“Our findings suggest that early dinosaur diversification was interrupted by climate-induced faunal replacement, at least in southwestern Pangea.”
A paper detailing this discovery was published in this week’s edition of Nature Ecology and Evolution.
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RN Martinez et al. Carnian theropods with unexpectedly derived features during the initial radiation of dinosaurs. Nat Ecol Evol published online October 14, 2025. doi: 10.1038/s41559-025-02868-4
Source: www.sci.news
